Six persons A ,   B ,   C ,   D ,   E and F are to be seated at a circular table facing…

There are two cases,
$\left(\mathrm{I}\right)$ is to the immediate right of $A$$.$

Number of ways $E$ can fill$=3$ ways

$E$ cannot take sit on the left of $A$ as there will be no space.

Number of ways $D$ can fill$=1$ ways

The remaining seats can be filled in 2 ways.

The total numbers of ways are $3\times 1\times 2=6$

The required number of ways are $12+6=18$